Interpretive mapmaking in the United States has a spotty history. The low point, urban planners agree, came in the 1930s, when bureaucrats at the federal Home Owners’ Loan Corporation produced maps of some 240 US cities showing each neighborhood’s average residential income. The maps were intended to help government officials implement a mortgage-relief program for distressed borrowers, but they turned out to be an ideal tool for those who wished to discriminate. Over the next few decades, private banks used the maps to justify their refusing mortgages to blacks in the poorest areas, on the basis that residents of these neighborhoods could be considered “high-risk.” Redlining, as the practice came to be called, was common in many US cities until the 1970s, when it was finally outlawed.

“Those maps were powerful because they were colorful, easy to interpret, and they told a clear story,” says Laura Kurgan ’90GSAPP, an associate professor of architecture and the director of Columbia’s Spatial Information Design Lab (SIDL) at the Graduate School of Architecture, Planning, and Preservation. “Would bankers have discriminated against residents in those areas anyway? Perhaps. But the maps made it easy. And back then, only small numbers of people had access to social data or the ability to visualize it, so not a lot of thematic maps were made. Those in existence were very influential.”

More data, more maps, more stories. More voices participating in a conversation about how to view our cities, address their problems, and serve their residents. That’s the goal of Kurgan and her colleagues at SIDL, who, for the past eight years, have been training civic organizations, nonprofit groups, and ordinary citizens to tell their own stories through thematic cartography: the practice of creating maps overlaid with statistical information.

SIDL researchers, working with collaborators around the world, have made maps that show where air quality in Beijing is worst, where traffic congestion in Nairobi could be alleviated, which Los Angeles neighborhoods are most dependent on immigrant labor, and which New York City streets frequently have trash pile up because of missed collections.

They even helped stop a New York City rezoning proposal. In 2009, with the city considering an ordinance to allow high-end commercial tenants into Manhattan’s Garment District — on the theory that the physical proximity of garment retailers and suppliers is less important in the Internet age — SIDL researcher Sarah Williams distributed cell phones equipped with global positioning system (GPS) technology to dozens of garment workers. She encouraged them to send SIDL a text every time they made a fabric delivery, trim pickup, or costume inspection. The resulting maps demonstrated that the garment workers were constantly dashing around the eight-block district; the City Council soon shelved the proposal.

“Some of our collaborators are nonprofit research groups that come to us for help displaying their findings,” says Kurgan. “In other cases, as with the garment workers, we’re helping citizens collect data and then create visuals to demonstrate something about their lives.”